I think it comes down to looks. The performance is so close, and the tuning potential for both cars is high enough to satisfy most enthusiasts, that it really comes down to looks. Out of the box, they're both great, and if you prefer one over the other in stock form, you can always add some aftermarket parts to make up the difference anyway. Personally, I just like the look of the STi better. I like the sound of the boxer motor, though I would probably tone down the wing and the scoop (maybe replace them with the regular WRX parts). That's just me though. Don't get me wrong, I love the 4G63 motor, but I just like the STi looks better.